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Nokia MPLS study materials
Nokia MPLS study resources

Nokia MPLS: Optical transport and data center interconnect

Nokia MPLS · Work through your exam, one topic at a time.

All guide sections

Optical transport and data center interconnect

Optical transport and data center interconnect

This domain covers Nokia 1830 PSS optical transport and DCI design: DWDM, ROADM, OTN, coherent optics, and Layer 2/3 DCI using EVPN-VXLAN.

Core rules

  • DWDM multiplexes wavelengths; flexgrid allows variable channel spacing. ROADM add/drop can be colorless, directionless, and contentionless (CDC).
  • OTN wraps client signals such as 100GbE into ODU4 and OTU4 for management, FEC, and long-haul reach.
  • Coherent optics such as 400G ZR/ZR+ plug into routers for DCI, trading reach and capacity; FEC and OSNR determine feasibility.
  • Layer 2 DCI uses EVPN-VXLAN over 7250 IXR/SR Linux; Layer 3 DCI uses VPRN/EVPN with IP routing.

Worked example

An 80 km dark-fiber span has 0.22 dB/km attenuation = 17.6 dB, plus 2 dB connector and margin = 19.6 dB. A 20 dB amplifier gain covers the loss, but check OSNR: too many spans or low launch power degrades OSNR. For 400G ZR+, verify reach against fiber type and FEC.

Traps

  • Confusing OTN ODU and OTU rates.
  • Assuming every ROADM is automatically CDC.
  • Ignoring fiber loss and connector budgets.
  • Using Layer 2 DCI without considering MAC scaling and EVPN multihoming.